The promise made to Abraham and his offspring that he should inherit the world, did not reach him through the Law, but through the righteousness of faith.

For if it is adherents of the Law who are heirs, then faith is empty of all meaning and the promise is void.

(What the Law produces is the Wrath, not the promise of God; where there is no law, there is no transgression either.)

That is why all turns upon faith; it is to make the promise a matter of favour, to make it secure for all the offspring, not simply for those who are adherents of the Law but also for those who share the faith of Abraham ??of Abraham who is the father of us all

no unbelief made him waver about God's promise; his faith won strength as he gave glory to God

they are not all children of Abraham because they are descended from Abraham. No, it is through Isaac that your offspring shall be reckoned ??8 meaning that instead of God's children being the children born to him by natural descent, it is the children of the Promise who are reckoned as his true offspring.

For when God said, I will come about this time and Sara shall have a son, that was a word of promise.